Spatiotemporal dynamics and driving factors of carbon sinks across ecosystems in Northwest China 后印本

摘要: Net ecosystem productivity (NEP) is a key indicator for estimating carbon sink dynamics in terrestrial ecosystems. Existing studies on carbon sink dynamics in Northwest China have uncertainties in quantifying spatiotemporal variations of NEP and their driving factors. This study estimated NEP across ecosystems in Northwest China during 2000–2020 using multi-model integration, and analyzed its spatiotemporal patterns and drivers. Results showed that the annual average NEP was 97.98 g C/(m2•a), with higher values at eastern and western margins and lower values in central hinterland. Strong carbon sink areas included the Yili River Basin and northern slope of Tianshan Mountains, while low carbon sink areas concentrated in eastern Xinjiang Uygur Autonomous Region (Eastern Xinjiang) and Alxa-Ejin Plateau. NEP trended upward from 79.22 g C/(m2•a) in 2000 to 109.03 g C/(m2•a) in 2020 with low variability and strong persistence, suggesting continuous growth. NEP significantly and positively correlated with near-infrared reflectance of vegetation (NIRv), weakly with climate factors, and negatively with socio-economic density indicators. Topographically, NEP peaked at 2.0–2.4 km elevation, 15°–25° slopes, and north-facing aspects. Changes in ecosystem type significantly influenced NEP, with bare land conversion into grassland/cropland enhancing carbon sinks. Results of this study highlight the need for ecological restoration and rational land use to boost carbon sequestration in this ecologically sensitive region.